METHOD OF CONTINUOUS HEAT TREATMENT OF LONG STEEL PRODUCTS AND DEVICE FOR ITS EMBODIMENT Russian patent published in 1997 - IPC

FIELD: metallurgy, particular, methods of heat treatment of such products as wire, narrow strip, sections, pipes of small diameters. SUBSTANCE: the offered method consists in the following: for instance, wire by means of pulling mechanism is passed through graphite with density of 0.5-1.8 g/cu.cm and heated in vacuum of 1-40 Pa up to austenite state. After heating, wire is rapidly cooled down to temperature of isothermal disintegration of austenite in steel by heat removal through graphite with density of 0.5-1.8 g/cu. cm compressed with force of 20-200 kg/sq.cm along direction of product movement. Then, effected in austenite state, with the help of reducing die is plastic deformation with degree of 2-20% and in flexible state with tension force of 0.5-1.0 of yield point of steel in austenite state, wire is pulled through zone of isothermal holding for 0.1-10 min with preset temperature of isothermal decomposition of austenite within (M_b+20)-650 C, where M_b is temperature of beginning of martensitic conversion in steel. Continuous heat treatment, according to the offered method, provides for increase of mechanical properties of product by 10-20% with comparable conditions of treatment, or reduces the required time of isothermal decomposition of austenite in steel by 20-40%. EFFECT: increased mechanical properties, and reduced time of isothermal holding to obtain optimal properties. 2 cl, 1 dwg, 1 tbl